Mechanical properties and microstructure characteristics of lattice-surfaced PEEK cage fabricated by high-temperature laser powder bed fusion

Abstract

• This paper proposes a novel lattice-surfaced PEEK cage to provide tailored mechanical performance, better stress absorption and deformation resistance. • The compression modulus and elastic limit can be tailored by adjusting the lattice-surfaced area without sacrificing the energy absorption efficiency. • Multiple point-plane stress transfer mechanism is found for lattice-surfaced PEEK cage, which plays an important role in stress absorption and deformation resistance. • The high-strength PEEK shows a characteristic radial morphology and a more ordered double-stranded orthorhombic structure. Porous structure design on the contact surface is crucial to promote the osseointegration of the intervertebral cage while preventing subsidence and displacement. However, the stress response will undergo significant changes for the current random porous cages, which can directly affect the mechanical properties and long-term usability. Here, this paper proposed a newly designed polyetheretherketone (PEEK) cage with the triply periodic minimal surface (TPMS)-structured lattice surfaces to provide tailored 3D microporosity and studied the mechanical performance, stress/strain responses, and microstructure changes in depth. The lattice-surfaced PEEK cage mainly exhibits a multiple-point-plane stress transfer mechanism. The compression modulus and elastic limit can be adjusted by controlling the area of the Diamond TPMS surface while the energy absorption efficiency remains stable. The microstructure of high-strength PEEK is featured by the radial pattern morphology. Meanwhile, the double-stranded orthorhombic phase is more ordered, and the benzene plane subunit and lattice volume become more expanded.